1. Technical Field
This invention relates in general to integrated circuits and, more particularly, to distributed power management of integrated circuits.
2. Description of the Related Art
Allocation of power in electronic circuitry is a primary concern in many areas, particularly in mobile circuitry, such as mobile telephones, PDAs (personal digital assistants), and other devices. As these devices become more complex and miniaturized, the need for effective power management increases, to both reduce power consumption (and, hence, optimize battery life) and to reduce heat generation.
In the past, power resources have been clustered in a single power management chip which supplies power to multiple hardware resources (such as different processors, including digital signal processors or “DSPs”, coprocessors, dedicated hardware circuits such as modems, and input/output circuitry). The number of power resources on the chip is limited by the heat dissipation of the package and the available number of pins. The power management chip has control logic, typically a finite state machine (FSM), which can be controlled by various hardware and software resources. If additional power is needed, it can be supplied by external power resources, but this will require additional pins on the chips using the external power resources and also separate control, since the control logic on the main power management chip does not control external power resources.
In addition to the problem of the number of power resources that can be housed on a single chip, and the control problems presented by the use of external power resources, the prior art has several drawbacks. First, the power control is not flexible, and thus a device intended for a first market sector may be unsuitable for use in a second market sector, due to different requirement in supply current and regulated voltages. Also, the prior art is not acceptable for shared power domains where isochronous power state transitions are needed.
Therefore, a need has arisen for a flexible and efficient power management system.